Power Enum allows you to treat instances of your ActiveRecord models as though they were an enumeration of values.
It allows you to cleanly solve many of the problems that the traditional Rails alternatives handle poorly if at all.
It is particularly suitable for scenarios where your Rails application is not the only user of the database, such as
when it's used for analytics or reporting.

Enumify lets you add an enum command to ActiveRecord models
There are four things that the enumify gems adds to your model
Validation - The enumify adds a validation to make sure that the field only receives accepted values
Super Cool Methods - adds ? and ! functions for each enum value (canceled? - is it canceled, canceled! - change the state to canceled)
Callback support - you can add a x_callback method which will be called each time the status changes
Scopes - you can easily query for values of the enum

Easy Attributes is a Ruby DSL to give more control to attributes. It provides a unique attribute enum setup, and conversions to bytes and float-as-integer (money, frequencies, Ratings, etc.) / fixed-decimal precision as integer (See the easy_money gem).